This invention relates to a technology for optimizing travel paths of a plurality of moving objects in order to carry out a predetermined task.
As a general method, a survey task for items of crops planted in farm fields is performed by a surveyor while searching for subject farm fields mainly depending on paper maps.
A car navigation system can be used for the above-mentioned survey task in an auxiliary manner, but part of farm roads, footpaths between farm fields, or the like are not normally registered in maps for the car navigation system. This is because it is harder to drive on a road having a predetermined width or smaller and it is therefore inappropriate for the car navigation system for general users to present the above-mentioned footpath or the like as the path.
Therefore, the car navigation system can be used by setting a vicinity of a survey subject farm field as a destination point, but after arriving at the destination point, the surveyor needs to search for the farm field depending on a paper map.
During the above-mentioned survey task, it is necessary to travel along a narrow farm road that is hard to pass through by car and a footpath that cannot be passed through by car, before reaching the survey subject farm field. Therefore, an optimization of a survey path is a optimization problem in consideration of a combination of traveling by automobile and traveling on foot.
As a solution to the above-mentioned problem, for example, there is known a technology for presenting an optimal path obtained by combining walking and traveling using public transportation (see, for example, JP 2003-106858 A). Further, there is known a method of searching for the optimal path in consideration of a station at which taxis and rental cars are available and a station at which taxis or rental cars are unavailable (see, for example, JP 2006-292447 A). With this method, it is possible to present a route for arriving at the destination earlier even after traveling a long distance as a result of using a taxi than a route for walking for a long time after getting off at the nearest station, and also possible to present a station at which the last train is late and taxis are available as a station to get off at instead of the nearest station.
In addition, there is known a technology for searching for the optimal path of each of a plurality of moving objects such as a walking person and an automobile in consideration of a case where a person traveling on the automobile gives a ride to the person traveling on foot on the way when the plurality of moving objects are heading from different departure points toward the same destination (see, for example, JP 2005-140664 A). Further, there is known a technology for searching for a travel path of a material handling robot for carrying medical materials such as medical supplies to a sickroom in place of a doctor or nurse (see, for example, JP 2005-288628 A).